| 摘要 |
PURPOSE:To simplify the bearing construction of a molecular pump by positively controlling three of the five freedoms excluding revolving speed of the rotor, supporting the resting two freedoms passively by magnetic bearings, and by operating the rotation by the inner rotor system. CONSTITUTION:A radial directed displacement sensor 1 senses the amount of displacement from the balance point in the diametric direction of the shaft 3, and this shaft 3 is stably restituted to the diametric balance point and held there by means of driving a diametric electromagnet 2 according to the signal given on the basis of the sensed displacement. For this purpose a couple of drive mechanisms are required in order to control the object in two directions independent from each other. In the axial direction, likewise, an axial directed displacement sensor 6 shall sense and drive an electromagnet 7 so as to hold the shaft 3 at the axially balanced point. According to this arrangement a passive support is provided by magnetic bearings, so that the bearing construction and drive circuit can be much simplified.
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